Re: [PATCH 1/2] software node: implement software_node_unregister()

From: Randy Dunlap <rdunlap@infradead.org>
To: Guenter Roeck <linux@roeck-us.net>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-kernel@vger.kernel.org
Cc: Naresh Kamboju <naresh.kamboju@linaro.org>,
	kernel test robot <rong.a.chen@intel.com>,
	stable <stable@vger.kernel.org>,
	Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
	Brendan Higgins <brendanhiggins@google.com>,
	Dmitry Torokhov <dmitry.torokhov@gmail.com>,
	Heikki Krogerus <heikki.krogerus@linux.intel.com>,
	Petr Mladek <pmladek@suse.com>,
	"Rafael J . Wysocki" <rafael.j.wysocki@intel.com>,
	Rasmus Villemoes <linux@rasmusvillemoes.dk>,
	Sakari Ailus <sakari.ailus@linux.intel.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Steven Rostedt <rostedt@goodmis.org>
Subject: Re: [PATCH 1/2] software node: implement software_node_unregister()
Date: Sun, 24 May 2020 19:44:16 -0700	[thread overview]
Message-ID: <13de8a28-9ea9-bf44-c4e7-d5bfb63c81fd@infradead.org> (raw)
In-Reply-To: <605c47b7-9199-85f1-89e0-bd768acd3d2d@roeck-us.net>

On 5/24/20 9:43 AM, Guenter Roeck wrote:
> On 5/24/20 8:30 AM, Greg Kroah-Hartman wrote:
>> Sometimes it is better to unregister individual nodes instead of trying
>> to do them all at once with software_node_unregister_nodes(), so create
>> software_node_unregister() so that you can unregister them one at a
>> time.
>>
>> This is especially important when creating nodes in a hierarchy, with
>> parent -> children representations.  Children always need to be removed
>> before a parent is, as the swnode logic assumes this is going to be the
>> case.
>>
>> Fix up the lib/test_printf.c fwnode_pointer() test which to use this new
>> function as it had the problem of tearing things down in the backwards
>> order.
>>
>> Fixes: f1ce39df508d ("lib/test_printf: Add tests for %pfw printk modifier")
>> Reported-by: Naresh Kamboju <naresh.kamboju@linaro.org>
>> Reported-by: kernel test robot <rong.a.chen@intel.com>
>> Cc: stable <stable@vger.kernel.org>
>> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
>> Cc: Brendan Higgins <brendanhiggins@google.com>
>> Cc: Dmitry Torokhov <dmitry.torokhov@gmail.com>
>> Cc: Heikki Krogerus <heikki.krogerus@linux.intel.com>
>> Cc: Petr Mladek <pmladek@suse.com>
>> Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
>> Cc: Randy Dunlap <rdunlap@infradead.org>
>> Cc: Rasmus Villemoes <linux@rasmusvillemoes.dk>
>> Cc: Sakari Ailus <sakari.ailus@linux.intel.com>
>> Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
>> Cc: Steven Rostedt <rostedt@goodmis.org>
>> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> 
> Both patches pass my boot tests on arm64 and arm64be (I didn't test any others).
> So, FWIW,
> 
> Tested-by: Guenter Roeck <linux@roeck-us.net>
> 
> I wasn't sure it the two patches replace or fix commit 4ef12f719802 ("kobject:
> Make sure the parent does not get released before its children"), so I tried
> to re-apply 4ef12f719802 on top of the two patches. Unfortunately that still
> results in crashes and UAF messages.

Yes, that kobject patch has been reverted:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e6764aa0e5530066dd969eccea2a1a7d177859a8

and these 2 patches are to be used instead.

thanks.
-- 
~Randy